Safety inner tube



0, 1954 H. K. CHANDLEY 2,685,905

SAFETY INNER TUBE Original Filed June 16, 1947 IN V EN TOR.

' Ai/RWKi/ii/ZZFF Patented Aug. 10, 1954 UNITED, STATES PATENT OFFICE Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio Original application June 16, 1947, Serial No. 754,993, now Patent No. 2,514,183, dated July 4, 1950. Divided and this application June 2, 1950,'Serial No. 176,932

2 Claims.

This invention relates to safety tubes for pneumatic tires of the type having a plurality of compartments, an inner and outer compartment in th present instance.

Pneumatic tire inner tubes now in general use are of a single tube type. In the event of a tire blowout, or a large rupture of the wall of a single compartment tube when such tube is in service the tire in which it is mounted will abruptly collapse. If, at the time the tire collapses, it is in service on a fast moving automobile, there is danger that the automobile on which it is mounted will go out of control of its driver and cause a serious wreck. I

To reduce to a minimum the danger to occupants of automobiles and property damage from sudden, or quick collapse of pneumatic tires in service, tire engineers, heretofore, have provided inner tubes with multiple air compartments. One such type tube now commercially available, comprises an inner and an outer air compartment so constructed that when the outer "compartment loses its air pressure and collapses, the inner compartment will sustain the load on the tire, in which it is mounted, for sufiicient time for a driver to bring a fast moving automobile safely to a stop. However, until the present invention, none such tubes have proven entirely satisfactory. One fault of the prior art was the high cost of the finished tube. Another fault of tubes heretofore commercially available was that. the wall of the inner compartment of the tube was at least partially vulcanized before it was attached to the wall of the outer compartment which made it very difiicult, if ever possible, to obtain a good union between the walls of the inner and outer com-' partment at their base portions. Upon the advent of high speed automobiles having sensitive steering controls, both dynamic and static balance of front wheels became an important requisite in avoiding shimmying of these wheels. A serious objection to safety tubes having an inner and an outer compartment has heretofore been that when installed they often threw wheels out of balance due to the out of balance of the tubes. A factor in causing th out of balance of such tubes was the wilting or drooping of the walls of the inner compartment during molding and vulcanization of the tubes.

An object of the invention is to provide a safety tube having an inner and an outer compartment whose longitudinal center lines lie in a plane dividing the tube base circumferentially in half and being at a right angle to the axis of the tube.

Another object of the present invention is to 2 provide a safety tube with inner and outer compartments wherein each compartment is formed of a complete tube.

Another object of the invention is to provide a plural compartment tube having an improved union betweenthe base portions of tubes forming the compartments.

Yet another object of the invention is to provide a multiple chamber safety inner tube so constructed that it may be cured with internal steam and substantially drained dry of conden sate.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings:

Fig. 1 is a perspective view of a finished tube embodying th present invention, and

Fig. 2 is an enlarged sectional view of the tube of Fig. 1 shown mounted in a tire on a tire rim with the tube inflated.

This application is a divisional application of my Patent No. 2,514,183 to whichreference is made for a disclosure of the method of making the tube described and claimed herein.

By reference to the drawing it will be seen that the invention comprises a complete outer tube II and a complete tube l2 lying entirely within tube I l. Tubes H and I2 have a common axis and are'adjoined in fluid-tight relation along their radial inner or base portion to an extent sufficient to extend from bead to bead of a tire mounted on its rim and in which tube I0 is adapted to be mounted and run in service. The tube l2 comprises two plies of rubberized cord tire fabric 14 and [5, the cords of which extend angularly transversely of the plies. Ply I5 is narrower than ply l4 and is disposed centrally thereof re sulting in a step-off of approximately between the edges of said plies. A layer of rubber I3 covers the entire exposed radial inner surface of the assembled plies I 4 and I5, said layer l3 extending a distance beyond the edges of said plies. A rubber base strip I 6 with its edges overlapping the edges of layer l3 closes the opening between the edges of layer I 3 forming a base portion of tube l2. Strip I6 is of greater thickness than layer l 3. A thickness of .020" for layer l3 and .060" for strip l6 has been found satisfactory for a 6.00-16 tube. Applicant provides an extent of rubber base between the edges of said rubberized fabric plies of approximately 4" for said 6.00-16 tire. Since 6.00-16 tires are mounted on rims 4" between their tire bead flanges, it will be seen that said rubber base will extend from bead to bead of a tire when said tube is run in service.

A molded rubber flutter valve l1, having a base I8, is attached to layer l3, with a longitudinallyflextendingihole throughwalve l- .|,.-a1i gned with a ,valvghole [9 @through the r alay er lpcgn d plies l4 and I5 of tube 12.

The outside tube ll comprises a continuous wall of rubber 20 which completely encloses tube l2 and adjoins strip 16 of tube l2 in fluid-tight relation therewith. Tube l .rl ha s,a greater section contour than tube rig, a substantial spacing of these tubesat their crown portions as will be seen by reference to the drawing.

A tire tube valve 33, which nay pagLggngentional type, is attached to th assembled tubes l l and I2 centered over a hole 25 passing through the strip l6 of tube l2 and the base =-of--wall 20 of tube 1 I at a point where said strip and base Q zwl u mare t uis rltieh l; i2n- Halve t trad-i r yinssi b ta ia lali n enttrans rse y of tube H], such alignment maki g po operation, tube Y, ID is mounted ,in a tire-. 49, e meen e tqn a i 1 a wil b see Th t yin at onary obtained b inflat n tube 16 t p essure 21 air under pressure as by the use of the usual a i $9 etafien r ir; -.c c-l and ai ;h se;.c nne .t t avza tablee ars o ;a .r. ,su p y- The walle im 1.11 bstent al y mnen iou :to ai bu thwpenia z hml flutte 'valv H i ,sue e to permit nfla ionar ai re eiv th ou said aback and v lv -1& it hine mo; e s ace 9 13 .tweenthe;tube 1 .a-n I l m u difierential air pressure bet ee erersine bmevea -e arti e 21.

immens 1. w .v .nctio as bei di sed within t ar e ube. :t b; said iulqe in substan iall 1. ;Qm .0e dl o rubbe t tne 'mi ,a ansiqn zunderiin ernal nsaid base having at least one lapped splice extending circumferentially thereabout, said splices -in said-separate bases being offset laterally withsaid 'oinedpreapf the bases, said bases hav- ;ing an nfiationary valve disposed in the joined 299*3955 2., inflatableifluid container of the class described adapted-fiche inserted in and removed jro n atire casing as a unit, comprising two con- ,eepjc c tgibes healing separate bases, said bases being composed of rubber only, one said tube beingiof smaller cross-section than the other and being disposed within the larger tube to form and met -llqim m eteatialzebam ersisa r a it e i n-bein :t ormed gflan an ula gheeto rubber; joined together to form a 2 the.-;p t r of sai tubes; bein :pom esed. o e sheet o rubbe hav n it opposite e es iszin dse he t cir umferent al la pe s ice th u ber censt uetionao said oute ,tub wpermi in expansion:unde ..:i terna1 :i il io t e bases :of e tubes 123112319 manen l Jo ned tes ther' :i .tfiuisiitieht relation f a ti-a1 extentnzinlan th e heu hei 1 mm head to. :bead

a ea e tendin :substae; of a tire in which said container may glee-,mounted in e viee s -.basesrhavin an inflation- .a z 'valy di p sed th n ipe tionsthereof, th aid-ante. n -e e splices of :th 1inner;and romeaq other with n t ;ne...1anent Joined circumferential he :inner-.=a d outer tubes, .-Qu entubmanchambers-marine ted..-; aesae th nebetweenr the, inner-of e b n co pos o :rubber ireinforced w th ebr eso e l-p si umci nt ri idity to e flationaryiair conth re 1 the. cu e .Beterences lq ediin t e file o thi aten :THNITED sures: PATENTS 

